Effect on South American CL: This
merges Harpyhaliaetus and “Leucopternis” (the temporary designation
for former Leucopternis species
definitely not members of that genus) into Buteogallus,
except for “L. plumbeus”, which would
become Cryptoleucopteryx plumbeus.

Background
& New Information:Our current classification looks like
this after passage of proposal 460,
which moved true Leucopternis and
relatives near Buteo:

For several
years, we’ve had plenty of indication that the current boundaries of genera in
the vicinity of Buteogallus in our
current classification are a mess.Raposo do Amaral et al. (2009) have produced a comprehensive phylogeny
of buteonine hawks, and their data will form the primary basis for this
proposal.Findings from earlier
papers (see Notes below) are largely consistent with Raposo do Amaral et al.
(2009) and will not be discussed further.Two of the relevant Notes from our SACC classification are:

14b. Buteogallus urubitinga was formerly treated in the monotypic genera Urubitinga(e.g., Hellmayr & Conover 1949) or Hypomorphnus
(Pinto 1938, Friedmann 1950, Phelps & Phelps 1958a), but see Amadon (1949) and Amadon & Eckelberry (1955)
for rationale for placement in Buteogallus. Genetic data (Lerner &
Mindell 2005), however, indicate that Buteogallus urubitinga and B.
anthracinus are not sisters and that the former is more closely related to Harpyhaliaetus
(see also Amadon 1949, Raposo et al. 2006). Raposo do Amaral et al. (2009)
recommended that they be treated in the genus Urubitinga.SACC proposal to revise generic limits in Buteogallus and relatives did not pass.

Raposo do
Amaral et al.’s (2009) taxon sampling (105 specimens, 54 species) and gene
sampling (6000 bp of 9 genes, mitochondrial and nuclear) is exemplary.I doubt that anyone will produce a
better data set anytime soon.This
proposal deals only with their Group H, whose monophyly has excellent support;
the relevant portion of their tree (from their Fig. 3) is pasted in here:

Therefore, the
problems in current classification are even worse than revealed in earlier
papers, with most species requiring a change in genus.Raposo do Amaral et al. had to name two
new genera to avoid combining all species into one large, heterogeneous Buteogallus.The latter solution is actually an
alternative to be explored if this proposal does not pass.Group H includes all the taxa previously
associated with Buteogallus, within
which generic limits have been historically fluid, and adds in three species
from Leucopternis, two of which are
dark like most of the Buteogallus
group but also one (lacernulatus)
that has more typical black-and-white Leucopternis
plumage.What a mess.At least one of the former Leucopternis, schistaceus, has a riverine habitat like its new sister taxa, Buteogallus sensu stricto.

Analysis and Recommendation: Virtually every critical node in Group H’s tree has strong
support.Therefore, the only point
of real discussion is the subjective exercise of how broadly to delimit the
genera.Raposo do Amaral et al.
have defined these very narrowly, but a proposal (459) to adopt that classification (see below) did not pass.

The option at
the other extreme would be to expand Buteogallus
to include all nine species in Group H.However, I am persuaded by the comments (see 459) of Kevin Zimmer and Bret Whitney, and by Gary Stiles’s
comments below (originally submitted as a NO vote to the previous version of
this proposal that was for a single broad Buteogallus)
that the outlier, “L.” plumbeus, placed in a newly described
genus Cryptoleucopteryx, merits a
monotypic genus.Although no single
character diagnoses it, it has a unique combination of characters, and plumbeus is also an oddball in terms of
voice and behavior.

A YES vote
would be to adopt the following classification by merging Harpyhaliaetus and two “Leucopternis”
into Buteogallus to produce the
following classification (which includes a minor sequence change mentioned by
Manuel in 459):

As expected
from a decision that is largely subjective, the comments on 459 were all over the place in terms of preference, but at
least a couple of you were in favor of broad Buteogallus.A point
against such a treatment is that if you look at the big tree in Raposo et al.,
the node (H) that unites a broad Buteogallus
is deeper than the points on the x-axis (substitutions/site) as the nodes that
mark most generic limits we adopted for the buteonines in proposal 460; so
based purely on comparable degree of genetic differentiation, a broad Buteogallus is within those limits but
at the extreme.On the other hand,
the depth of that node is driven entirely by plumbeus – if not for that species, the node would be at the
opposite end of the range of the depths that mark generic boundaries in the
buteonines.To maximize consistency
based on genetic differentiation, a solution would be to adopt Cryptoleucopteryx for plumbeus and keep the rest in Buteogallus (a solution mentioned by
Doug in his comments on 459).

“1. I definitely favor placing plumbeus in Cryptoleucopteryx,
based largely on Kevin`s comments on the previous proposal and the large
genetic distance to the rest of the "Buteogallus
group". I am not disturbed by the "lack of a single diagnostic
character": a unique combination of characters serves to diagnose many
avian genera. The single-character requirement harks back to a century
ago, when such characters in taxonomic keys dictated generic boundaries -
rather like putting the cart before the horse. Actually, we haven't been all
that consistent in use of genetic vs. morphological-ecological-behavioral
features and generic boundaries in any case ... after all, we recognized Cantorchilus based on genetics when the
morphological evidence was, as far as I could tell, zero, and did not recognize
Diglossopis as separate from Diglossa based on relatively short
genetic distances but in the face of considerable morphological, behavioral and
ecological differences.And there
have yet to be advanced good morphological diagnoses for some genera in
Furnariidae (e.g., the Asthenes-Schizoeaca assemblage). So, it comes
down to rather subjective decisions in any case regarding how to weigh the
different types of evidence when they do not coincide neatly.

“2. Regarding placing all the remainder of this group
in a broad Buteogallus, I could buy
it, albeit with some reservations.The only real oddball (at least in terms of appearance) is lacernulatus, but genetics strongly
favors including it, especially if we also include meridionalis, which I find much less surprising: its juvenile
plumage is decidedly buteogalline, its coloration as adult is not so unlike aequinoctialis, its vocalizations are
also not greatly unlike some Buteogallus.Although more terrestrial than others, urubitinga also forages much on the
ground and has decidedly longish legs as well. I have already remarked
upon the resemblance of solitarius
and urubitinga, such that I see no
objection to considering these as congeners, which pretty much bridges the
gaps; so, unless there is strong support for the original proposal of Raposo et
al. (including two monotypic genera for meridionalis
and lacernulata and separating Urubitinga), the next best choice would
indeed be two genera: Cryptoleucopteryx
and Buteogallus.”

Comments from Robbins: “YES.This is a subjective decision, but as I
mentioned in my comments on proposal # 459, the vocal and morphological
variation within a broadly defined Buteogallus
are no more than that found within Buteo.
With regard to genetic variation and consistency among nodes in taxonomy
and nomenclature, I'm fine with placing plumbeus
in a monotypic genus.This is
somewhat analogous with what we did in naming a new genus for the highly
genetically divergent, but morphologically indistinct (vocalizations are still
unknown), Malagasy Gactornis "Caprimulgus" enarratus (although that was a very long branch).”

Comments from Cadena: “YES. I am not a great fan of monotypic genera; whenever possible, unless
one is truly dealing with hoatzin-like oddballs, I prefer having genera with more
than one species. I believe this increases the information content of the
classification because one immediately knows that two species in the same genus
are close relatives, whereas if one has two separate monotypic genera for
sister lineages, their close affinity is essentially unknowable based on the
names alone. Thus, I like the expanded Buteogallus
over the use of the two monotypic genera Amadonastur
and Heterospizias. I'll take other's
word that plumbea is the hoatzin
equivalent in these raptors (I am afraid I do not know all these taxa all that
well), so I am OK with Cryptoleucopteryx.”

Comments
from Jaramillo: “YES.I think that
this is a good resolution to this problem. Using a monotypic genus for plumbeus
is the better solution as opposed to a broad and genetically too (?) divergent
single Buteogallus that includes all of the species. Having a broad Buteogallus
is a benefit, and a better solution in my mind, than is separating it out into
3-4 genera.”

Comments
from Zimmer: ““YES.I agree
with Fernando in having a preference for more narrowly defined genera, although
readily acknowledge that having a bunch of monotypic genera isn’t all that
informative.I think Van has come
up with a good compromise in this case, by recognizing the distinctiveness of plumbeus by placing it in a monotypic
genus Cryptoleucopteryx, and placing
everything else in a broadly defined Buteogallus.As Gary points out, it is not much of a
stretch to see the similarity of meridionalis
to urubitinga (ecologically, morphologically
[especially as regards juvenile plumage], vocally) and to aequinoctialis (plumage characters of adults and juveniles).Same goes for the two species of Harpyhaliaetus and for schistaceus and anthracinus.The one
that still doesn’t feel right is lacernulatus
(which is pretty different morphologically, is a forest interior hawk that
frequently soars, etc.), but then we have to contend with the genetic data and
the apparent close relationship between lacernulatus
and meridionalis.All in all, I think this is a good
compromise.”